marines to australia. >> romney hasn't commented on those moves. instead, he's charged obama with not being tough enough with china on trade. >> china has been a currency manipulator for years and years and years. and the president has a regular opportunity to label them as a currency manipulator, but refuses to do so. >> the president has responded with some tougher trade moves of his own. >> we've put unprecedented trade pressure on china. that's why exports have significantly increased under my presidency. that's going to help to create jobs here. >> but dealing with china ahead is going to be about a lot more than trade, says brookings scholar o'hanlon. >> us-china relations are undoubtedly one of the more complicated matters for any future american president. and for the rest of our lives this relationship is going to be the most important, perhaps, and perhaps the most difficult. >> on that, and so many other issues, the public will have to wait until after the election to get a clearer sense of how differently either man would handle it. >>